PURPOSE: To provide a process for producing 4,4'-diisocyanato dicyclohexylmethane contg. at least 90 wt.% trans, trans-isomer.
CONSTITUTION: (a) A mixture composed of the 4,4'-diisocyanato dicyclohexylmethane contg. at least 30 wt.% trans, trans-isomer is solvated; (b) this molten mixture is cooled to about 0 to 25°C to form (1) a liquid phase contg. about 12 to 25 wt.% trans, trans-isomer and (2) a solid phase contg. about 70 to 85 wt.% trans, trans-isomer; (c) this liquid phase is removed; (d) this solid phase is heated to about 60 to 83°C and the molten part of the solid phase is removed to incorporate about 35 to 65 wt.% trans, trans-isomer into this melt and (e) the product generated by heating the remaining part to about 90°C is made to contain about 90 wt.% trans, trans-isomer, by which the undissolved part of the solid phase is recovered.
KENESU ERU DANRATSUPU
MAIKERU KEI ROUERII
TERII EI POTSUTAA
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